A wide variety of flowable downhole tools may be used within a wellbore in connection with well servicing operations (as well as completion operations and the production of oil and/or gas therefrom). Fracturing (frac) balls, for example, may be introduced into a wellbore to operate another downhole device. In one application, a fracturing ball is introduced into a work string or other tubular flowed via gravity and/or the circulation of wellbore fluids to a seat or other receiving apparatus. The ball engages the seat thereby forming a seal and preventing further fluid flow through the work string or tubular, and hydraulic pressure builds up behind it. This hydraulic pressure may be used to operate the device, e.g. to open a valve or actuate a sliding sleeve in the device. In another application, a frac ball contains a signaling device, such as a transceiver. As the frac ball traverses the wellbore communicates with one or more downhole devices in furtherance of a production or workover operation.
In many instances, it is desirable or necessary to retrieve or otherwise consume the frac ball at some point during or after a given servicing operation is complete. However, retrieval may be difficult or impossible, such as in cases where the frac ball becomes stuck, for example when a frac ball cannot be unseated or when there is insufficient wellbore circulation to produce a frac ball from the well. Stuck fracturing balls can decrease the profitability of a well by, for example, reducing the production rate or requiring expensive remedial operations.
Thus, it would be desirable for frac balls to be more easily removed (e.g., produced) from a wellbore. It would also be desirable to develop frac balls from materials that allow the frac ball to be more easily removed (e.g., produced) from a wellbore and that can also withstand downhole hydrostatic pressures, including those encountered in subsea wellbores.
Another example of flowable downhole tools used in furtherance of well servicing operations are plugs. Conventionally, cementing a casing string within a wellbore is achieved by flowing cement to the bottom of the casing string and upward into the annular space between the casing string and the wellbore walls. In order to preserve the integrity of the cementitious slurry used to cement the casing within the wellbore, “cementing plugs” or “wiper plugs” are used to form a barrier between the cementitious slurry and other servicing fluids, for example, to reduce intermixing or intermingling between the cementitious slurry and any other fluid. In applications where the core of a cementing plug is drilled to facilitate fluid flow therethrough (e.g., after a cementing operation), it may be desirable to clear the drilled parts from the newly created flowpath so that the fluid may flow unobstructed. Thus, it would be desirable to develop cementing plugs that may be easily removed from the wellbore.